Deflection electrode device for an ink jet printing apparatus

ABSTRACT

A deflection electrode device for an ink jet printing apparatus. A pair of vertical and a pair of horizontal deflection electrodes, the electrodes of which each have a groove for sucking ink deposited on the electrodes therein under capillary action, are disposed on the apparatus perpendicular to each other in a radial, spaced-apart arrangement about the ink stream.

[ Jan. 15, 1974 DEFLECTION ELECTRODE DEVICE FOR AN INK JET PRINTING APPARATUS [75] Inventor:

[73] Assignee: Casio Computer Co., Ltd., Tokyo,

Japan [22] Filed: Dec. 13, 1971 [21] Appl. No.: 207,320

Toshio Kashio, Tokyo, Japan [30] Foreign Application Priority Data Dec. 16, 1970 Japan 45/125400 Dec. 16, 1970 Japan 45/125401 [52] US. Cl. 346/75, 317/3 [51] Int. Cl. Gold 15/18 [58] Field of Search 346/75, 140; 317/3; 239/15, 4

[56] References Cited UNITED STATES PATENTS 3,656,169 4/1972 Kashio 346/75 X 2,676,868 4/1954 Jacob 346/75 3,136,594 6/1964 Ascoli 346/75 X 3,373,437 3/1968 Sweet et a]. 346/75 3,458,762 7/1969 Ascoli 3,657,599 4/1972 Kashio Primary Examiner Joseph W. Hartary Attorney-Allison C. Collard [57] ABSTRACT I A deflection electrode device for an ink jet printing apparatus. A pair of vertical and a pair of horizontal deflection electrodes, the electrodes of which each have a groove for sucking ink deposited on the electrodes therein under capillary action, are disposed on the apparatus perpendicular to each other in a radial, spaced-apart arrangement about the ink stream.

4 Claims, 7 Drawing Figures PATENTED 5 3,786,516

A mmmnnnnnm VIIIIIII III FIG. 3

DEFLECTIQN ELECTRODE DEVICE FOR AN INK JET PRINTING APPARATUS The present invention relates to a deflection electrode device for an ink jet printing apparatus.

In conventional ink jet printing devices, ink is jetted as a stream of small droplets from a nozzle toward a recording medium by an acceleration means using electrostatic force, electromagnetic force, ultrasonic force or the like, and the ink droplets are deflected by deflection electrodes to print out the desired letters, character patterns or the like on the recording medium. Since these deflection electrodes, which are unlike deflection electrodes which are mounted in Braun tubes or cathode ray tubes for deflecting electron beams, deflect the flying ink particles, the ink particles are frequently deposited on the deflection surfaces of the deflection electrodes. The deflection surfaces thus become dirty, and as a result, conventional deflection electrodes can not maintain their desired deflection characteristics.

It is, therefore, an object of the present invention to overcome the above difficulty, and to provide a deflection electrode device which can maintain a desired deflection characteristic even when ink particles are deposited on the deflection surfaces of the deflection electrodes, and thereby exhibit stable operation.

According to the present invention, the above object is accomplished by a deflection electrode device for an ink jet printing apparatus which includes a pair of vertical and a pair of horizontal deflection electrodes, the electrodes of which eachhave a groove for sucking or drawing ink deposited on the electrodes therein under capillary action.

The present invention can be more fully understood from the following detailed description when taken in conjunction with reference to the appended drawings, in which:

FIG. 1 is a sectional view for illustrating one embodiment of a deflection electrode device according to the present invention;

FIG. 2 is an exploded perspective view of the deflection electrode device shown in FIG. 1;

FIG. 3 is a sectional view taken along the line AA of FIG. 2 looking in the direction of the arrow shown in FIG. 2;

FIG. 4 is a perspective view of another embodiment of the deflection electrode for use in the embodiment of FIg. 2;

FIG. 5 is an exploded perspective view of the deflection electrode shown in FIG. 4; and

FIGS. 6 and 7 are perspective views of further embodiments of the deflection electrodes for use in the embodiment of FIG. 2.

The sectional view shown in FIG. 1 and the exploded perspective view shown in FIG. 2 illustrate the same embodiment and hence the same reference numerals are used for the corresponding parts in both drawings. A fine tube 11 of glass forming an ink nozzle is fitted into a metal pipe 12 for protection purposes, which metal pipe, in turn, is fitted into a holding member 13 of insulating material. Coupled to the rear end of the metal pipe 12 is a vinyl pipe 14 for feeding ink. In front of and laterally of the nozzel 11, an acceleration electrode 15 is positioned to enclose the nozzle 11 in spaced relationship, and it is secured to the holding member 13. The acceleration electrode 15 has a bore 16 formed at a position on a line coaxially extending from the glass tube 11. The acceleration electrode 15 is enclosed by a deflection electrode holding frame 17 of insulating material, which has a bore larger than bore 16 for the acceleration electrode 15. Glass tube 11, metal pipe 12, holding member 13, acceleration electrode 15 and holding frame 17 are assembled sequentially, in that order, and are secured together as an integral unit by suitable fastening means.

A pair of vertical electrodes 21 and 31 and a pair of horizontal electrodes 41 and 51 are mounted on holding frame 17 by bolts 29, 39, 49 and 59. Electrodes 21,

31, 41 and 51 consist of metal plates of about 1 mm thickness, and have bores 22, 32, 42 and 52 for receiving the bolts, and grooves 23, 33, 43 and 53 for sucking the ink. Deflection electrode plates 21, 31, 41 and 51 have projections 24, 34, 44 and 54 respectively, and are positioned on holding frame 17 in such a way that end surfaces 25 and 35 and end surfaces 45 and 55 face each other, respectively.

In the operation of the ink jet printing apparatus, appropriate deflection control voltages are applied between the opposing vertical deflection electrodes 21 and 31 and between the opposing horizontal deflection electrodes 41 and 51. The end surfaces 25, 35, 45 and 55 of the respective electrodes 21, 31, 41 and 51 act as deflection surfaces to generate a deflection field in a space defined by the deflection surfaces 25, 35, 45 and 55. In this particular embodiment, since the deflection electrodes are positioned in in a plane normal to the path of the flying ink particles to define a space by the four deflection surfaces, that is, since a vertical deflection field and a horizontal deflection field generated by the deflection surfaces are introduced in said space, the deflection of the jet ink may be easily and precisely controlled by the deflection electrodes.

Each of the four deflection electrodes 21, 31, 41 and 51 has on its deflection surfaces 25, 35, 45 and 55, a deep groove 23, 33, 43 or 53 or about 0.1 0.2 mm width. The grooves are illustrated in FIG. 3, which is a cross-sectional view of electrode 51 taken along line A-A of FIG. 2. As illustrated in the drawings, groove 53 is formed on the end surface 56 of the projection 55 and extends sufficiently deep therein to divide projection 55 into two parts and reach the rear end of electrode 51. The other electrodes 21, 31 and 41 are substantially the same as electrode 51.

In the operation of the ink jet printing apparatus of the present invention, the ink, to which a predetermined amount of pressure is applied through an appropriate pressure means, not shown, is supplied from the vinyl pipe 14 to the glass tube 11, and a predetermined voltage is applied from a voltage source, not shown, between acceleration electrode 15 and the ink to jet the ink particles from ink nozzle 11. The ink droplets are introduced through bore 16 in acceleration electrode 15 into the space defined by deflection surfaces 25, 35 45 and 55 of the deflection electrodes. Between vertical deflection electrodes 21 and 31 and horizontal deflection dlectordes 41 and 51 are applied vertical and horizontal deflection voltages respectively, by a controlled voltage supply means, not shown. Accordingly, the ink jet stream is deflected in the space defined by deflection surfaces 25, 35, 45 and 55 to depict a desired character, letter or the like on a recording medium, disposed opposite to the ink jet.

During the printing operation, if the ink droplets jetted are deposited on deflection electrodes '21, 31, 41

and 51, the deposited ink is sucked into grooves 23, 33, 43 and 53 under the capillary action of these grooves. As a result, the deflection field induced by deflection surfaces 25, 35, 45 and 55 is not disturbed, and a precise and stable deflection characteristic is maintained. The grooves are so deep, as shown in FIG. 3, that they draw in and retain a sufficient amount of deposited ink to prevent interference with the deflection field during printing.

The structure of each of the electrodes forming the deflection electrode device, which includes the four de flection electrodes shown in FIG. 1, may be that of an electrode 81 shown in FIGS. 4 and 5. Electrode 81 comprises a pair of metal plates 91 and 93 of about 0.5 mm thickness, and a smaller metal plate 92 of about 0.1 0.2 mm thickness, interdisposed between metal plates 91 and 93. Metal plates 91 and 93 and second metal plate 92 have a bore 82 formed therein for receiving a bolt. The structure formed by the first pair of metal plates and the second plate interdisposed therebetween is laminated to secure the plates together. The plates form a deep groove 83 which extends from end surface 85 of tip projection 84. Groove 83 sucks in any ink deposited on the electrode.

FIGS. 6 and 7 illustrate further embodiments of the deflection electrode structures. The electrode 101 of FIG. 6 has a groove 103 on end surface 105 of projection 104 which is the same as groove 53 shown in FIGS.

2 and 3, and another groove 106 which is perpendicular to groove 103. A bore 102 is provided to receive a bolt for fastening the electrode. Electrode 111 of FIG. 7 has a groove 113 on end surface 115 of a projection 114 thereof, which is the same as groove 53 shown in FIGS. 2 and 3, and two additional grooves 116 and 117 which are perpendicular to groove 115. The electrode also has a bore 112 for receiving a bolt.

While only a single embodiment of the present invention has been shown and described, it will be obvious tothose persons skilled inthe art that many changes and modifications may be made thereunto without de parting from the spirit and scope of the invention.

What is claimed is:

1. In an ink jet printing apparatus in which ink is jetted in a stream of small droplets from an outlet nozzle towards and onto a recording medium by an acceleration means utilizing electrostatic, electromagnetic, or ultrasonic force, and the like, a deflection electrode device for deflectingthe direction of the ink stream comprising:

a pair of vertical deflection electrodes affixed to the ink jet printing apparatus, and pair of horizontal deflection electrodes affixed to the ink jet printing apparatus adjacent said first pair of vertical deflection electrodes, said horizontal and vertical deflection electrodes have elongated grooves extending along their length adjacent to the ink stream for drawing ink deposited on said deflection electrodes therein and wherein the ends of said horizontal and vertical deflection electrodes are disposed in a radial, spaced-apart relationship around the ink stream, said grooves open on said ends of said electrodes adjacent said ink stream, said electrodes being metallic plates, shaped so as to have a first enlarged section, and a second section having a width less than said first section, said second section being radially inwardly disposed towards said ink stream, said grooves ineluding slots disposed in one side of said electrodes and extending lengthwise along said electrodes through said first and second sections.

2. The deflection electrode device as recited in claim 1, wherein said vertical and horizontal deflection electrodes are affixed to the ink jet printing apparatus so that they are disposed within a plane perpendicular to the direction of the stream of the ink particles, and so that said vertical deflection electrodes are vertically disposed and said horizontal defection electrodes are horizontally disposed, and said vertical and horizontal electrodes are disposed perpendicular to each other.

3. The deflection electrode device as recited in claim 1, wherein said electrodes comprise,

a pair of first metal plates, and

a second metal plate, substantially smaller in dimensions than said first meta] plates, interdisposed between said pair of metal plates, said plates being laminated to secure said plates together to form said electrodes with said grooves being formed between said first pair of metal plates about the periphery of said electrodes.

4. The deflection electrode device as recited in claim 1, wherein said electrodes further comprise at least one additional groove, disposed in said second section of said electrodes perpendicular to said groove extending lengthwise therein, for sucking ink deposited on said electrodes therein. 

1. In an ink jet printing apparatus in which ink is jetted in a stream of small droplets from an outlet nozzle towards and onto a recording medium by an acceleration means utilizing electrostatic, electromagnetic, or ultrasonic force, and the like, a deflection electrode device for deflecting the direction of the ink stream comprising: a pair of vertical deflection electrodes affixed to the ink jet printing apparatus, and a pair of horizontal deflection electrodes affixed to the ink jet printing apparatus adjacent said first pair of vertical deflection electrodes, said horizontal and vertical deflection electrodes have elongated grooves extending along their length adjacent to the ink stream for drawing ink deposited on said deflection electrodes therein and wherein the ends of said horizontal and vertical deflection electrodes are disposed in a radial, spaced-apart relationship around the ink stream, said grooves open on said ends of said electrodes adjacent said ink stream, said electrodes being metallic plates, shaped so as to have a first enlarged section, and a second section having a width less than said first section, said second section being radially inwardly disposed towards said ink stream, said grooves including slots disposed in one side of said electrodes and extending lengthwise along said electrodes through said first and second sections.
 2. The deflection electrode device as recited in claim 1, wherein said vertical and horizontal deflection electrodes are affixed to the ink jet printing apparatus so that they are disposed within a plane perpendicular to the direction of the stream of the ink particles, and so that said vertical deflection electrodes are vertically disposed and said horizontal defection electrodes are horizontally disposed, and said vertical and horizontal electrodes are disposed perpendicular to each other.
 3. The deflection electrode device as recited in claim 1, wherein said electrodes comprise, a pair of firSt metal plates, and a second metal plate, substantially smaller in dimensions than said first metal plates, interdisposed between said pair of metal plates, said plates being laminated to secure said plates together to form said electrodes with said grooves being formed between said first pair of metal plates about the periphery of said electrodes.
 4. The deflection electrode device as recited in claim 1, wherein said electrodes further comprise at least one additional groove, disposed in said second section of said electrodes perpendicular to said groove extending lengthwise therein, for sucking ink deposited on said electrodes therein. 